This invention relates to imaging internal body portions of animals.
Animals, especially mammals, are dependent upon having an adequate oxygen supply in their body tissues. In mammals, the circulatory system employs specialized oxygen-carrying molecules in the blood to deliver oxygen from the lungs to other tissues throughout the body. Thus, every organ in the body contains oxygen in varying amounts and concentrations in every tissue. The distribution of oxygen in tissue can be indicative of structure, anomalies, defects or disease.
It is known that oxygen can have a quenching effect on the molecular luminescence of various aromatic chemical compounds and that this property can be used in the measurement of oxygen concentrations as shown in Stevens, U.S. Pat. No. 3,612,866. Bacon et al, in U.K. patent application No. GB 2,132,348A, published July 4, 1984, disclose inter alia using a fluorescent material to measure levels of oxygen in blood both in vitro and in vivo using a fiber optic probe or catheter.
An optical technique for imaging internal body structures based on the varying oxygen concentration of tissue which is not invasive or otherwise harmful would be very useful. For example, it could be used in examining soft body tissue for anomalies in the vasculature which generally accompany tumor formulation, and for obtaining detailed diagnostic information on many types of vascular defects, e.g., constrictions, varicosities, or aneurisms.
The inventors of this invention have previously disclosed methods for measuring oxygen concentration in biological systems using oxygen-dependent phosphorescent quenching of lumiphores. See Vanderkooi and Wilson, "A New Method for Measuring Oxygen Concentration in Biological Systems" Oxygen Transport to Tissue VIII, Longmuir, ed, Plenum (August, 1986). No method of imaging using such techniques has been known heretofore, however.